Introduction
 |
Yesterday, Sigma announced two new wide-angle lenses for L-mount and Sony E-mount camera systems: the 20mm F1.4 DG DN and the 24mm F1.4 DG DN. We’ve gone hands-on with the pair of them to see what features they offer and what sets them apart from the competition.
Users and use cases
 |
Both of these lenses are part of Sigma's 'Art' DN series, which also includes its 35mm F1.2 DG DN, 35mm F1.4 DG DN, 85mm F1.4 DG DN and 105mm F2.8 DG DN Macro lenses. These are Sigma's highest-quality lenses (optically speaking) and its two newest offerings are the widest of the bunch. The 20mm/24mm duo also rounds out the F1.4 lenses in Sigma's 'Art' lineup, which Sigma is considering a sub-series of sorts in the Art lineup.
In the case of the 20mm F1.4, it's clear Sigma has made this lens for astrophotographers. While it could surely be used for other genres of photography, its feature set targets astrophotographers and Sigma's own marketing material for the lens almost exclusively refers to astrophotography as the use-case for this optic.
By comparison, the 24mm F1.4 lens is a more versatile lens that could easily work in the bag of any still photographer or cinematographer. On full-frame cameras, it offers a wide perspective great for vlogging, landscapes, architecture and astrophotography and on crop sensors, it offers a roughly 35mm full-frame equivalent angle-of-view, great for everything from portraits to street photography.
Buttons and switches
 |
The two lenses are very similar in terms of their respective interfaces. Both lenses offer AF/MF switch, Manual Focus Lock (MFL) switches (more on this in the next slide), a (de)click switch and an aperture lock switch.
As you might expect, the AF/MF switch controls whether you’re shooting with autofocus or manual focus, the (de)click switch lets you control whether or not the aperture ‘clicks’ into place with each 1/3EV movement and the aperture lock switch prevents you from accidentally rotating the aperture ring to ‘Auto’ when making adjustments.
There's also an Autofocus Lock (AFL) button that can lock autofocus into place and also be customized to control other functions if your workflow requires it.
Manual Focus Lock
 |
Focus-by-wire is becoming the standard focusing mechanism in modern lens design and while focus-by-wire brings some advantages, it does have some pitfalls compared to its direct-drive counterparts. Most notably, these lenses tend to reset the focus when the camera goes into power save mode or is turned off. to combat this issue, Sigma has added a new Manual Focus Lock (MFL) switch.
This switch will deactivate the focus ring entirely, locking focus at the spot it was when the switch is activated. In the case of astrophotography, this means you can focus on the stars, activate the MFL switch, and not worry if your camera accidentally falls asleep or you move to another location and turn off your camera. As soon as you power it back on, the lens will still have focus right where you left it, regardless of whether or not the focus ring was rotated by accident.
Lens Heater Retainer
 |
Lens heaters are rarely used outside the world of astrophotography, but for those that need them, they're a game-changer. For the uninitiated, these little devices wrap around the barrel of a lens and keep the lens from getting cooler than the surrounding air, which can result in the lens fogging up, ruining an otherwise fantastic shot.
Sigma's new Lens Heater Retainer, which is limited to the 20mm F1.4, attempts to further satiate the needs of astrophotographers by creating a little protrusion on the front-most part of the lens barrel that's specifically designed to keep lens heaters in place so they can't slide off the lens and end up ruining your otherwise beautiful night sky timelapse. It's a small touch, but goes to show how much Sigma sees the 20mm F1.4 as an astrophotography optic.
Rear filter holder
 |
Both of these optics offer rear gel filter holders. While not out of the ordinary for wide-angle lenses, what is interesting is that both lenses can be used with both rear filters and front filters through their respective front filter threads.
Using a template provided with the lenses, you can cut out various gel filters that slot into a little indentation underneath the electronic contacts of the lens. The bottom indentation is then slipped beneath a little switch, which you can slide over to effectively lock the filter in place with some tension.
We haven’t had the time to cut out gels and use them on our lenses, but the above images show the stencil overlaid on the rear mount of the lens, as well as a side view that shows a little gap around the entire back panel of the lens that the gel is meant to sit within.
These two optics appear to be the first lenses that offer both front and rear filter holders. Usually, manufacturers rely on rear filter holders when the front-most element protrudes beyond the barrel of the lens, but in the case of Sigma's 20mm and 24mm F1.4 lenses, you can double up on filters without the need of any specialized attachments.
Optical design (20mm F1.4 DG DN)
 |
Sigma’s 20mm F1.4 DG DN lens is constructed of 17 elements in 15 groups, including two Super-Low Dispersion (SLD) elements and three aspherical elements. These three aspherical elements include a pair of double-sided aspherical elements that Sigma says helps to control comatic aberration (coma) across the entire frame for sharp images from edge to edge.
In our time with the lens, these elements appear to work as advertised, resulting in sharp images from the center of the frame to the edge of the frame with minimal coma, even at wider apertures. As visible in our sample gallery,
Optical design (24mm F1.4 DG DN)
 |
Sigma’s 24mm F1.4 DG DN lens is constructed of 17 elements in 14 groups, including two ‘F’ Low-Dispersion (FLD) elements, one Super-Low-Dispersion (SLD) element and four aspherical elements.
Sigma says this construction with its specialized elements is designed to suppress optical aberrations, but our experience with the lens shows coma isn’t nearly as well controlled with the 24mm F1.4 as the 20mm F1.4. Still though, once stopped down to F2.8 or beyond, the lens is very sharp across the frame with no visible vignetting. Sun stars look good through the lens when stopped down, but we noticed some rainbow flaring when shooting at specific angles.
Competition
 |
Both of these lenses offer impressive features and specifications, but how do they hold up against their contemporaries? Turns out, it's a bit of a difficult question to answer. While Sigma does have its non-DN equivalents for both of these lenses, those are larger and not specifically designed to make the most of the shorter flange distance of mirrorless cameras.
Sony does have its 20mm F1.8 G and 24mm F1.4 G lenses, both of which offer impressive image quality, but Sony's 20mm F1.8 is 2/3EV slower for the same price and Sony's 24mm F1.4 costs $500 more than Sigma's equivalent lens, which also has additional quality-of-life features, such as the Manual Focus Lock and aperture lock switch.
As for other L-mount competition (aside from the aforementioned Sigma HSM lenses), there isn't really any competition.
Summary
 |
In all, these two wide-angle lenses from Sigma add compelling offerings to owners of L-mount and Sony E-mount camera systems. Sure, the focal lengths might be similar, but it's clear the 20mm F1.4 is made with a very specific market in mind: astrophotographers. The 24mm, on the other hand, is a more well-rounded option that's been a staple focal length in the photography world going back decades.
The 24mm F1.4 has some stiff competition in the E-mount market, but its pricing drives a hard bargain, offering what is shaping up to be respectable performance at a price nearly $500 less than Sony's 24mm F1.4 GM.
Sigma's 20mm F1.4 and 24mm F1.4 are set to ship in 'late August 2022' at $799 and $899, respectively. They are currently available to pre-order from authorized retailers.
from Articles: Digital Photography Review (dpreview.com) https://ift.tt/hZOi8Fm
via IFTTT
0 comments: